Congressional leaders yesterday promised a tough review and reassessment of the nation's space program -- including the feasibility of continuing the costly international space station -- in the wake of last week's Columbia shuttle disaster.

Even as NASA officials struggle to determine the precise cause of the accident that killed seven astronauts, lawmakers plan to begin hearings next week that will challenge the wisdom of the administration's long-term goals of completing the space station project and developing a replacement for the aging shuttle fleet, as well as examine the causes of the shuttle disintegration.

"This tragedy will force some policy decisions that are long overdue," said Sen. John McCain (R-Ariz.), chairman of the Commerce, Science and Transportation Committee and a critic of the space station. "What is the purpose of the space station? Do the cost overruns and participation of Russia and other nations make it realistic? What should be the role of unmanned exploration?"

McCain said he will hold the hearings with the House Science Committee beginning Wednesday with testimony from NASA Administrator Sean O'Keefe on details of the shuttle accident.

Rep. Sherwood L. Boehlert (R-N.Y.), chairman of the Science Committee and a major supporter of the space program, said he informed O'Keefe during a private session with lawmakers Monday evening that the hearings will be far reaching and will explore shortcomings in NASA's operations and policymaking as well as possible failures on the part of Congress.

"We want to examine if policies may have led to the loss of the Columbia, and then determine whether policy changes need to be made," Boehlert said in an interview.

Since the shuttle disaster, lawmakers from both parties have echoed President Bush's assertion that the space program must continue. But they suggested that Congress would play a more aggressive oversight role in the months to come, as it assesses whether NASA shortchanged the shuttle's safety program.

Rep. Dana Rohrabacher (R-Calif.), who is chairman of the House Science subcommittee on space and aeronautics, said he and others warned for more than a year that the shuttle system was aging but that the National Aeronautics and Space Administration had wasted billions in trying to develop a replacement.

Lawmakers said the more immediate problem is to determine what to do about the space station, the most ambitious project ever attempted by NASA that is billions of dollars over budget, far behind schedule and of dubious value in conducting cutting-edge scientific research.

Two American astronauts and a Russian cosmonaut are aboard the orbiting space lab. But with the remaining shuttles grounded indefinitely, until NASA can pinpoint and fix the problems that led to Saturday's Columbia disaster, officials face a dilemma with the space station. The crew, if necessary, can return to Earth on a Russian ship docked to the space station. But it is unclear how the United States can get additional supplies to the space station or send up a replacement crew with the future of the shuttle so uncertain.

The station requires periodic nudges from visiting shuttles to help it maintain its orbital position and resist atmospheric drag. Without that assistance, the space station would eventually fall out of orbit.

"We're going to have to determine the importance of the space station and whether we want to continue it," said Rep. Bart Gordon (D-Tenn.), a House Science Committee member. "It isn't an option to rely on the Russians" to get to and from the space station.

Gordon recalled that when the Challenger was destroyed in 1986, it took 21/2 years before the shuttle fleet was back in service. "If that happens again, we will see a $100 billion investment fall out of the sky."

Senate Commerce Committee Chairman John McCain (R-Ariz.), left, plans to ask NASA Administrator Sean O'Keefe, right, about the space station and other questions in hearings with House Science Committee next week.